Guralp Systems CMG-DM24S12AMS User Manual

Page 68

CMG-DM24S12AMS Operator's guide

7. Drag the other down to be level with the highest point. In the

following example, a step function of 1 minute duration has been

applied to the Z3 stream. Note that ground movements continue
to be observed, superimposed on the returning calibration signal.

The Ampl Cursors button will now be displaying a value, which
is the strength of the returning signal in counts (doubled, if using

a sine wave). Measure the other two signal strengths in this

manner.

Note that if you have used the Scale... option described above,
you will need to take the scale factor into account to produce the

correct number of counts. In the example, the MB (calibration

input) signal has been scaled by a factor of 40, so the signal
strength as measured by the Ampl Cursors must be divided by 40
to yield the correct value.

8. Convert to volts using the µV/Bit values given on the digitiser's

calibration sheet for the various input ports, and compare the
returned signal with the input calibration signal (MB).

9. In the example, the following data is now known:

Issue B